<!doctype HTML>
<html>
<meta charset="utf8">
<title>Content Visibility: off-screen focus</title>
<link rel="author" title="Vladimir Levin" href="mailto:vmpstr@chromium.org">
<link rel="help" href="https://drafts.csswg.org/css-contain/#content-visibility">
<meta name="assert" content="content-visibility auto element remains non-skipped when elements in its subtree have focus.">

<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>

<style>
body, html {
  padding: 0;
  margin: 0;
}

.spacer {
  height: 3000px;
  background: lightblue;
}
#container {
  background: lightgreen;
  contain-intrinsic-size: 50px 100px;
  content-visibility: auto;
}
#focusable {
  width: 10px;
  height: 10px;
}
</style>

<div class=spacer></div>
<div id=container>
  <div id=focusable tabindex=0></div>
</div>
<div class=spacer></div>

<script>
async_test((t) => {
  // Initially container should be 3000px offscreen with contained height 100px.
  function step1() {
    const r = container.getBoundingClientRect();
    t.step(() => {
      assert_equals(r.y, 3000, "step1 offset");
      assert_equals(r.height, 100, "step1 height");
    });

    focusable.focus();
    requestAnimationFrame(step2);
  }
  // After focusing the subtree, the container should be somewhere closer than
  // 3000px (scrolled into view) and the height should be 10px, since it no
  // longer has containment.
  function step2() {
    const r = container.getBoundingClientRect();
    t.step(() => {
      assert_less_than(r.y, 3000, "step2 offset");
      assert_equals(r.height, 10, "step2 height");
    });
    document.scrollingElement.scrollTop = 0;
    requestAnimationFrame(step3);
  }
  // After scrolling the document back to the top, the container should be back
  // at 3000px but because its subtree is still focused, it should have height
  // 10px.
  function step3() {
    const r = container.getBoundingClientRect();
    t.step(() => {
      assert_equals(r.y, 3000, "step3 offset");
      assert_equals(r.height, 10, "step3 height");
    });
    requestAnimationFrame(step4);
  }
  // This is a repeat of step3, to ensure that this is a stable state.
  function step4() {
    const r = container.getBoundingClientRect();
    t.step(() => {
      assert_equals(r.y, 3000, "step4 offset");
      assert_equals(r.height, 10, "step4 height");
    });
    focusable.blur();
    requestAnimationFrame(step5);
  }
  // After blurring the focused element, we should go back to the contained
  // height of 100px.
  function step5() {
    const r = container.getBoundingClientRect();
    t.step(() => {
      assert_equals(r.y, 3000, "step5 offset");
      assert_equals(r.height, 100, "step5 height");
    });
    t.done();
  }
  step1();
});
</script>
</html>
